The present invention relates generally to the field of trenchers, and more particularly to a trencher with a foldable rock saw wheel.
There are basically three types of trenching machines; bucket wheel, chain type, and disk (or saw). Bucket wheels are basically for softer materials, and the chain type and disk type are better suited for hard rock trenching, but all can be used for soft material trenching. A typical chain or saw trencher has a digging boom or frame that is connected to a tractor. Chain type trenchers are capable of much wider and deeper trenching than the disk type. However, they have two problems. First, the chain will wear much quicker. Second, a wider trench must be cut in order to provide clearance for the chain. The disk or saw type trencher typically cuts shallower and narrower than an equivalent size chain type trencher. It has a rigid wheel, typically in the form of a round, solid metal disk, and cutters attached around the wheel""s outer circumference or periphery.
As a disk wears much better than a chain, the total cost of using a disk or saw for trenching can be significantly less. However, digging deeper trenches requires use of a larger diameter saw. Because a trencher with a large saw must be transported to a digging site on the back of a trailer, with the saw mounted on the boom, height restrictions on public roadways limit the size or diameter of a rock saw on a trencher. Many trenchers are designed to allow use of both saw and chain attachments. Deeper trenches are preferred for burying fiber optic and other comparatively fragile cables. Doing so reduces the risk of the cable being accidentally cut during subsequent construction.
The present invention concerns an improved saw for a trenching machine. According to the invention, a trenching machine includes a rock saw wheel with at least one section that can be folded and/or removed. This separate section permits transporting a trenching machine with a rock saw wheel that would otherwise be too large for transport or to obtain a permit for transport on public roadways without completely disassembling the wheel. Thus, deeper trenches can be dug using a saw or disk trencher with a lower total cost of operation.
One example of a trenching machine employing one or more teachings of the invention has a rock saw wheel with at least one section or piece separate from a main portion of the wheel. The main portion of the wheel is mounted to the trencher. At least one of the one or more separate sections is attached to the main portion during normal operation by one or more connecting plates that span at least a portion of a seam where the foldable section abuts the main portion of the wheel. One or more removable fastenersxe2x80x94bolts, for examplexe2x80x94connect the plate(s) to the main portion and to a section. The plates thereby provide rigidity to the wheel for operation. The fasteners are removed to allow the separate section to be folded to a side or removed altogether, which reduces the diameter of the rock saw in one direction to a size that allows for transport over public roadways.
It is preferred that one connecting plate for at least one separate section be attached at one end to the main portion so that it pivots, such as by use of a hinge or similar mechanism. Thus, the separate section remains connected to the main portion of the wheel, but folded or pivoted to the side during transport of the trenching machine. With a pivoting connection, the separate section can be swung into place and assembled for operation with fewer steps and without, in the case of very large wheels, the need for additional lifting equipment. It also avoids having to separately stow the section on the trailer. Furthermore, it is preferred that the pivoting connection be of a type that permits disconnecting the separate section for removal should a reduction in transport weight as well as a height reduction be needed.
A preferred embodiment of the invention is further described below with reference to the accompanying drawings.